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If the equation (m+6)x^(2)+(m+6)x+2=0 ha...

If the equation `(m+6)x^(2)+(m+6)x+2=0` has real and distinct roots, then

A

`mlt-6`

B

`mgt2`

C

`-6ltmlt2`

D

`mlt-6ormgt2`

Text Solution

AI Generated Solution

The correct Answer is:
To determine the values of \( m \) for which the quadratic equation \( (m+6)x^2 + (m+6)x + 2 = 0 \) has real and distinct roots, we need to analyze the discriminant of the quadratic equation. ### Step-by-Step Solution: 1. **Identify the coefficients**: The given quadratic equation can be rewritten in the standard form \( ax^2 + bx + c = 0 \), where: - \( a = m + 6 \) - \( b = m + 6 \) - \( c = 2 \) 2. **Write the discriminant**: The discriminant \( D \) of a quadratic equation \( ax^2 + bx + c = 0 \) is given by: \[ D = b^2 - 4ac \] Substituting the values of \( a \), \( b \), and \( c \): \[ D = (m + 6)^2 - 4(m + 6)(2) \] 3. **Simplify the discriminant**: Expanding \( D \): \[ D = (m + 6)^2 - 8(m + 6) \] \[ D = (m + 6)(m + 6 - 8) \] \[ D = (m + 6)(m - 2) \] 4. **Set the condition for real and distinct roots**: For the roots to be real and distinct, the discriminant must be greater than zero: \[ (m + 6)(m - 2) > 0 \] 5. **Find the critical points**: The critical points occur when \( D = 0 \): \[ m + 6 = 0 \quad \Rightarrow \quad m = -6 \] \[ m - 2 = 0 \quad \Rightarrow \quad m = 2 \] 6. **Test the intervals**: We will test the sign of \( (m + 6)(m - 2) \) in the intervals defined by the critical points: - Interval 1: \( (-\infty, -6) \) - Interval 2: \( (-6, 2) \) - Interval 3: \( (2, \infty) \) - For \( m < -6 \) (e.g., \( m = -7 \)): \[ (-7 + 6)(-7 - 2) = (-1)(-9) > 0 \] - For \( -6 < m < 2 \) (e.g., \( m = 0 \)): \[ (0 + 6)(0 - 2) = (6)(-2) < 0 \] - For \( m > 2 \) (e.g., \( m = 3 \)): \[ (3 + 6)(3 - 2) = (9)(1) > 0 \] 7. **Conclusion**: The intervals where \( (m + 6)(m - 2) > 0 \) are: \[ m < -6 \quad \text{or} \quad m > 2 \] ### Final Answer: Thus, the values of \( m \) for which the equation has real and distinct roots are: \[ m < -6 \quad \text{or} \quad m > 2 \]
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